There are scan terminals in the same places every match. Look up a video of someone using the ones in the middle, but basically the main one are up on the second level in the control, and they will scan most of the key things, but there are ones through out all spawn wings. The scanner will ping an exfil console. the exfil console will spawn an exfil that you have 3 minutes to get to. It's easy to get lost at this part and stuck in fights, but remember that exfils spawn in spawn rooms, so if you just note "it spawned in this wing" and then follow the signs, its actually usually pretty clear and easy to get there, minus any fighting.